Planar optical waveguides enjoy widespread use in optical communications technology, including switches, filters and multiplexers. Stability of the index of refraction, ni, of the waveguide material is desirable to maintain device operation within a desired tolerance. However, the ni of such materials commonly varies as a function of temperature. Such variability is commonly defined by a nonzero value of the thermo-optic coefficient (TOC), or ∂n/∂T.
In many cases, required performance stability of an optical system necessitates controlling the temperature of a waveguide to maintain the ni of the waveguide within design tolerances. Such temperature control imposes costs and complexity on system design and manufacture.